1. Technical Field
The present disclosure generally relates to the Held of optical sensor probes for collection of luminescence generated at a dielectric interface, and more particularly, an optical sensor probe employing a parabolic optical waveguide optimized for the efficient collection of luminescence generated at a dielectric interface.
2. Description of the Related Art
Optical sensors are widely used across a broad range of industrial applications in industries including, for example, biomedical, environmental and food packaging. Luminescence-based optical sensors detect analyte-induced changes in a luminescence signal. Such changes may be brought about due to the analyte-induced quenching of luminescence from an analyte-sensitive luminescent compound, which is the case for a broad range of optical chemical sensors including sensors for oxygen, carbon dioxide, pH and chloride. In such cases, the luminescent compound is typically encapsulated within a porous, solid matrix that can be deposited onto a substrate as a thin film. Alternatively, luminescence-based optical sensors may be based on the binding of the analyte of interest to a surface using suitable receptor molecules. Luminescence is imparted to such a system through the use of a luminescent label that can be attached to the analyte itself or to an additional molecule that binds to the surface-bound analyte. Changes in the level of luminescence are indicative of changes in the concentration of analyte that is bound to the surface. This methodology is commonly employed for the development of luminescence-based optical biosensors.
In order to sensitively measure the concentration of analyte molecules bound to the receptor molecules, it is necessary to detect only the luminescence that originates from surface-bound molecules. From this, it follows that the measurement task is to detect selectively luminescence from molecules bound close to the surface, excluding any signal from unbound molecules in the environment above the surface. This detection principle, is also relevant to thin film-based optical chemical sensors.
An understanding of the nature of luminescence emission at a dielectric surface is necessary in order to efficiently detect luminescence and develop effective optical chemical/biological sensors. The anisotropic nature of this emission has prompted the development of novel optical configurations designed to more efficiently capture luminescence that has been generated at or near a dielectric surface, for example, U.S. Pat. No. 6,714,297 to Seeger and Ruekstuhl, which is hereby incorporated herein by reference. That reference describes the detection of supercritical angle fluorescence (SAF), which is generated by luminescent molecules located at or near a dielectric surface by using a parabolic optical waveguide. This detection ability improves the amount of fluorescence that can be detected in addition to being a surface-selective detection mechanism.
Unfortunately, current optical arrangements are costly and it is often difficult to change optical components in the event that the user would like to monitor a variety of analytes. Additionally, many of these optical arrangements have low efficiency due to the fact that their ability to collect emitted luminescence is limited.
Therefore, it would be desirable to provide a robust, low-cost, portable optical sensor probe that is capable of the efficient detection of luminescence for the development of highly-sensitive sensors. The sensor probe should incorporate an apparatus that allows for the efficient collection of surface-generated luminescence and the detection principle can be intensity-based or lifetime-based depending on the desired application. The probe should also be modular in nature, facilitating the detection of a variety of analytes using the correct combination of sensing material and optical/optoelectronic components.